I am not sure but if you are using a shiva (I am using a tempest, already have it, just finished the box) you can use lspcad which is a bit more comprehensive. After re-creating your alignment in lsp cad go to the "box/filter/eq" menu and go to equaliser, you will get the predicted effects of the equaliser.

I am guessing you know what the frequency and boost amount is (35hz and 6db), You could say that the Q is the "width" of the boost with the lower the number the wider the area that it affects. For the jaycar amp i would stick it at around 1 for an estimate.